Running for his third consecutive term, Nolan said he was proud of his efforts over the last two years to counter the loss of almost 10,000 mining jobs in the district.

He touted his testimony at the International Trade Commission and his invitation to President Obama's chief of staff to visit the district last year to hear about the suffering firsthand. Since then, the U.S. Department of Commerce has implemented anti-dumping tariffs on seven countries dumping steel illegally into the market, which could boost the market for U.S. iron ore.

"We have seen an increase in ore prices and an increase in steel consumption. ... I have worked on this more than any other member of Congress," said Nolan, speaking directly to Mills: "And I didn't see you there."

Mills shot back that the economy on the Iron Range is not improving.

"People are still getting pink slips, people are still unemployed," he said.

Mills and Nolan are in a rematch to represent the Eighth Congressional District, which includes Duluth and most of northeastern Minnesota. It has been a Democratic stronghold for decades, but Republicans have made inroads in the last few election cycles.

On health care, Mills said he favored repealing the Affordable Care Act, which he called a "disaster." He didn't specify how he wanted to replace it, but said he was in favor of state-based social safety nets.

Nolan said he wanted a universal single-payer health care system — similar to Medicare — as an option for the uninsured and he wanted the government to be able to negotiate contracts with the pharmaceutical industry for prescription drugs.

The two also disagreed on how to keep guns away from terrorists. Nolan said he favored prohibiting gun sales to people on terrorist watch lists.

Mills said those terrorist lists are run by bureaucrats and said that, instead, "we should go in and arrest those people." Mills twice noted Nolan's "F" rating from the National Rifle Association.

Mills said the higher education system could be improved by creating a "students bill of rights" that would, among other things, guarantee credit transfers from one school to another.

Nolan retorted that a credit from "Trump University" should not be treated the same as credits from more reputable schools. GOP presidential candidate Donald Trump's namesake real estate schools are facing a federal lawsuit after allegations they defrauded students, a charge Trump denies.

Nolan and Mills also clashed over the minimum wage, an increasingly polarizing issue as some cities around Minnesota and the nation consider raising the base wage.

Mills called it unconstitutional for the federal government to set a national minimum wage. Nolan responded that the courts have ruled a federal minimum wage to be constitutional.